iommu: Factor out some helpers

The pattern for picking the first device out of the group list is
repeated a few times now, so it's clearly worth factoring out, which
also helps hide the iommu_group_dev detail from places that don't need
to know. Similarly, the safety check for dev_iommu_ops() at certain
public interfaces starts looking a bit repetitive, and might not be
completely obvious at first glance, so let's factor that out for clarity
as well, in preparation for more uses of both.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/566cbd161546caa6aed49662c9b3e8f09dc9c3cf.1700589539.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f17a1113f3d6a35daf9cff1def8f4f5158416ea2..5c555fc0d54ca2d19bd61d86c14792c5e87622f1 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -368,6 +368,15 @@ static void dev_iommu_free(struct device *dev)
        kfree(param);
 }
 
+/*
+ * Internal equivalent of device_iommu_mapped() for when we care that a device
+ * actually has API ops, and don't want false positives from VFIO-only groups.
+ */
+static bool dev_has_iommu(struct device *dev)
+{
+       return dev->iommu && dev->iommu->iommu_dev;
+}
+
 static u32 dev_iommu_get_max_pasids(struct device *dev)
 {
        u32 max_pasids = 0, bits = 0;
@@ -620,7 +629,7 @@ static void __iommu_group_remove_device(struct device *dev)
 
                list_del(&device->list);
                __iommu_group_free_device(group, device);
-               if (dev->iommu && dev->iommu->iommu_dev)
+               if (dev_has_iommu(dev))
                        iommu_deinit_device(dev);
                else
                        dev->iommu_group = NULL;
@@ -819,7 +828,7 @@ int iommu_get_group_resv_regions(struct iommu_group *group,
                 * Non-API groups still expose reserved_regions in sysfs,
                 * so filter out calls that get here that way.
                 */
-               if (!device->dev->iommu)
+               if (!dev_has_iommu(device->dev))
                        break;
 
                INIT_LIST_HEAD(&dev_resv_regions);
@@ -1225,6 +1234,12 @@ void iommu_group_remove_device(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(iommu_group_remove_device);
 
+static struct device *iommu_group_first_dev(struct iommu_group *group)
+{
+       lockdep_assert_held(&group->mutex);
+       return list_first_entry(&group->devices, struct group_device, list)->dev;
+}
+
 /**
  * iommu_group_for_each_dev - iterate over each device in the group
  * @group: the group
@@ -1752,23 +1767,6 @@ __iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
        return __iommu_group_domain_alloc(group, req_type);
 }
 
-/*
- * Returns the iommu_ops for the devices in an iommu group.
- *
- * It is assumed that all devices in an iommu group are managed by a single
- * IOMMU unit. Therefore, this returns the dev_iommu_ops of the first device
- * in the group.
- */
-static const struct iommu_ops *group_iommu_ops(struct iommu_group *group)
-{
-       struct group_device *device =
-               list_first_entry(&group->devices, struct group_device, list);
-
-       lockdep_assert_held(&group->mutex);
-
-       return dev_iommu_ops(device->dev);
-}
-
 /*
  * req_type of 0 means "auto" which means to select a domain based on
  * iommu_def_domain_type or what the driver actually supports.
@@ -1776,7 +1774,7 @@ static const struct iommu_ops *group_iommu_ops(struct iommu_group *group)
 static struct iommu_domain *
 iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
 {
-       const struct iommu_ops *ops = group_iommu_ops(group);
+       const struct iommu_ops *ops = dev_iommu_ops(iommu_group_first_dev(group));
        struct iommu_domain *dom;
 
        lockdep_assert_held(&group->mutex);
@@ -1854,7 +1852,7 @@ static int iommu_bus_notifier(struct notifier_block *nb,
 static int iommu_get_def_domain_type(struct iommu_group *group,
                                     struct device *dev, int cur_type)
 {
-       const struct iommu_ops *ops = group_iommu_ops(group);
+       const struct iommu_ops *ops = dev_iommu_ops(dev);
        int type;
 
        if (!ops->def_domain_type)
@@ -2021,7 +2019,7 @@ bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
 {
        const struct iommu_ops *ops;
 
-       if (!dev->iommu || !dev->iommu->iommu_dev)
+       if (!dev_has_iommu(dev))
                return false;
 
        ops = dev_iommu_ops(dev);
@@ -2120,11 +2118,9 @@ static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,
 static struct iommu_domain *
 __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type)
 {
-       struct device *dev =
-               list_first_entry(&group->devices, struct group_device, list)
-                       ->dev;
+       struct device *dev = iommu_group_first_dev(group);
 
-       return __iommu_domain_alloc(group_iommu_ops(group), dev, type);
+       return __iommu_domain_alloc(dev_iommu_ops(dev), dev, type);
 }
 
 struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
@@ -2987,8 +2983,8 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
  */
 int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
 {
-       if (dev->iommu && dev->iommu->iommu_dev) {
-               const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
+       if (dev_has_iommu(dev)) {
+               const struct iommu_ops *ops = dev_iommu_ops(dev);
 
                if (ops->dev_enable_feat)
                        return ops->dev_enable_feat(dev, feat);
@@ -3003,8 +2999,8 @@ EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
  */
 int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 {
-       if (dev->iommu && dev->iommu->iommu_dev) {
-               const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
+       if (dev_has_iommu(dev)) {
+               const struct iommu_ops *ops = dev_iommu_ops(dev);
 
                if (ops->dev_disable_feat)
                        return ops->dev_disable_feat(dev, feat);